The production of silicon from a mixture of silicon dioxide (generally quartz rock) and carbon can be carried out conventionally in an electric furnace with an overall reaction described by the equation SiO.sub.2 +2C=Si+2CO. As can be seen from this equation two moles of carbon are required to react with a mole of silicon dioxide to yield one mole of silicon and two moles of carbon monoxide.
When silicon oxide and carbon are reacted in an electric furnace by conventional techniques, however, it is not always possible to ensure quantitative transformation of silicon dioxide to elemental silicon because silicon carbide may be produced by local reactions of the following form: SiO.sub.2 +3C=SiC+2CO.
The electric furnaces which are used are mainly electrical low-shaft furnaces coming in metallurgical applications. As used herein, moreover, the term "quartz" will be employed to mean any silicon dioxide carrier capable of reacting with carbon to produce elemental silicon. Such raw materials include sand, quartzites and comminuted quartz rock.
When the above described reactions are carried out, as described, for example, at column 3, lines 4 through 19 of German Patent Document No. 20 55 564, a loose mixture and bed are formed from quartz and carbon without prior formation of agglomerates.
During the course of the reaction an intermediate in the form of silicon monoxide may be formed which undergoes disproportioning and hence the overall reaction involves cyclical reduction and reformation of silicon dioxide. This has been found to limit the yield and to be associated with increased energy consumption.